Silver Attached Graphene-Based Aerogel Composite Phase Change Material and the Enhancement of Thermal Conductivity

Abstract

Phased energy storage technologies are highly advantageous and feasible for storing and utilizing clean renewable energy resources, for instance, solar energy and waste heat, and it is an effective method to improve energy efficiency and save energy. However, phase change energy storage has some problems, for example, low thermal conductivity and phase change leakage, which lead to limited application. In this paper, anisotropic graphene aerogels were prepared by ice crystal template method with high thermal conductivity of graphene, and silver was attached to the pore wall graphene sheets and the graphene sheet boundaries of the aerogels. The results show that anisotropic graphene aerogels were successfully prepared, and SEM and EDS indicate that up to 9.14 at % silver was successfully attached to the graphene sheets and boundaries. The anisotropic thermal conductivity of the PArGO phase change composites after adsorption of the paraffin is significant, with a maximum axial thermal conductivity of PArGO of 1.20 W/(mK) and radial thermal conductivity of 0.54 W/(mK), compared to the pure paraffin (0.26 W/(mK)) increased by 362% and 108%, respectively. The enthalpy of the composite has been reduced to 149.6 J/g due to the silver particles attached, but the thermal properties have been greatly improved. In experiments simulating real temperature changes, PArGO achieves phase transitions very fast, with a 74% improvement on thermal efficiency of storage and discharge over the pure paraffin.

Multi-Stimuli-Responsive Aerogels Composed of Ag Nanoparticle-Coated Graphene Nanosheets for Energy Storage and Conversion

“…In addition, the T m and T c of pure PW are 54.08 and 49.19 °C, and the Δ H m and Δ H c reach 137.00 and 141.37 J/g, respectively. Compared to pure PW, the slightly decreased T m and T c for PW-GAA may be explained by that the high thermal conductivity of the GAA skeleton enables rapid heat transfer, thus accelerating the phase transition process . However, it can be clearly observed that the latent heat of phase change for composite PCMs decreases to different degrees with increasing AgNP content compared to that of pure PW (Figure c), with H m and H c fluctuating roughly between 130.70 and 136.62 J/g and between 135.00 and 140.43 J/g.…”

“…Compared to pure PW, the slightly decreased T m and T c for PW-GAA may be explained by that the high thermal conductivity of the GAA skeleton enables rapid heat transfer, thus accelerating the phase transition process. 38 However, it can be clearly observed that the latent heat of phase change for composite PCMs decreases to different degrees with increasing AgNP content compared to that of pure PW (Figure 5c), with H m and H c fluctuating roughly between 130.70 and 136.62 J/g and between 135.00 and 140.43 J/g. It is evident that the thermal energy storage and release of composite PCMs are highly dependent on the weight percentage of PW since the GA and GAA skeletons hardly behave as phase transition.…”

Aerogels Meet Phase Change Materials: Fundamentals, Advances, and Beyond

“…The longitudinal thermal conductivity of the obtained composite PCMs was 0.79 W/m•K when the content of rGO/EG aerogels was 8.7 wt %, which was almost four times higher than pristine paraffin. Similarly, Zhang et al 128 prepared anisotropic graphene/silver hybrid aerogels using an ice crystal template method. During the preparation process, silver was tightly attached to the interfaces of graphene nanosheets to reduce the thermal resistance between graphene and PCMs.…”

Healable supramolecular micelle/nano-encapsulated metal composite phase change material for thermal energy storage

“…25 In the preparation of composite organic PCMs, due to the high contact surface area of additives and high capillary, they can transfer heat to the absorbent of PCMs very well, and thus avoid liquid leakage. 23,26 Therefore, due to the properties of silver, it is selected as an additive dispersed in PCMs to improve the thermal properties of the composite. Then, silver nanoparticles are synthesized via an in situ reduction strategy and encapsulated via phase change selfassembled micelles (APPG).…”